1. Field of the Invention
The present invention relates to brachytherapy devices, and more particularly to an increased strength, flexible, radioactive source ribbon assembly having an additional containment layer.
2. Discussion of the Related Art
Percutaneous transluminal coronary angioplasty (PTCA) is a therapeutic medical procedure used to increase blood flow through an artery and is the predominant treatment for coronary vessel stenosis. The increasing popularity of the PTCA procedure is attributable to its relatively high success rate and its minimal invasiveness compared with coronary by-pass surgery. Patients treated utilizing PTCA; however, may suffer from restenosis. Restenosis refers to the re-narrowing of an artery after a successful angioplasty procedure. Restenosis usually occurs within the initial six months after an angioplasty. Early attempts to alleviate the effect of restenosis included repeat PTCA procedures or by-pass surgery, with attendant high cost and added patient risk.
Restenosis is now believed to occur at least in part as a result of injury to the arterial wall during the lumen opening angioplasty procedure. In some patients, the injury initiates a repair response that is characterized by hyperplastic growth of the vascular smooth muscle cells in the region traumatized by the angioplasty. Intimal hyperplasia or smooth muscle cell proliferation narrows the lumen that was opened by the angioplasty, regardless of the presence of a stent, thereby necessitating a repeat PTCA or use of other procedures to alleviate the restenosis.
Recent studies indicate that intravascular radiotherapy (IRT) has promise in the prevention or long-term control of restenosis following angioplasty. Intravascular radiotherapy may also be used to prevent or delay stenosis following cardiovascular graft procedures or other trauma to the vessel wall. Proper control of the radiation dosage; however, appears to be important to inhibit or substantially arrest hyperplasia without causing excessive damage to healthy tissue. Underdosing will result in inadequate inhibition of smooth muscle cell hyperplasia, or possibly even exacerbation of hyperplasia and resulting restenosis.
Radiation therapy may also be utilized in the treatment of other diseases such as cancerous and non-cancerous tumors or other proliferative normal tissue disorders. In this type of therapy, the ultimate aim is to destroy the malignant tissue without causing excessive radiation damage to nearby healthy and possibly vital tissue. This is difficult to accomplish because of the proximity of malignant tissue to healthy tissue.
Brachytherapy is a form of radiation treatment in which an ionizing radiation source, for example, an intravascular radiotherapy source ribbon, is placed into or adjacent to a tumor or stenotic lesion. Although any number of radioactive substances and/or radioactive sources may be utilized in brachytherapy, lodine-125 is currently a good candidate isotope for vascular brachytherapy. Iodine-125 has been used as a liquid or immobilized onto a variety of surfaces for diagnostic and therapeutic purposes. It has already been fashioned into a variety of shapes and used clinically for cancer treatment as briefly described above.
The radioactive source ribbon assembly of the present invention provides a means for overcoming the difficulties associated with the devices currently in use as briefly described above.
In accordance with one aspect, the present invention is directed to a radioactive source ribbon assembly. The radioactive source ribbon assembly comprises an outer jacket adapted for use with a delivery catheter, a radiation resistant load bearing sleeve mounted within the outer jacket, and a radioactive source positioned within the radiation resistant load bearing sleeve.
In accordance with another aspect, the present invention is directed to a radioactive source ribbon assembly. The radioactive source ribbon assembly comprises a substantially tubular outer jacket having a proximal end and a distal end, the substantially tubular outer jacket being adapted for use with a delivery catheter, a substantially tubular radiation resistant axial load bearing sleeve mounted with the outer jacket, a radioactive source positioned in a distal portion of the radiation resistant axial load bearing sleeve, a core positioned in a proximal portion of the radiation resistant axial load bearing sleeve adjacent to the radioactive source and proximal and distal seals mounted to the proximal and distal ends of the substantially tubular jacket for sealing the jacket.
In accordance with another aspect, the present invention is directed to a radioactive source ribbon assembly. The radioactive source ribbon assembly comprises a substantially tubular outer jacket having a proximal end and a distal end, the substantially tubular outer jacket being adapted for use with a delivery catheter, a substantially tubular radiation resistant axial load bearing sleeve mounted within the outer jacket, a substantially tubular inner jacket mounted within the substantially tubular radiation resistant axial load bearing sleeve, a radioactive source positioned in a distal portion of the substantially tubular inner jacket, a core positioned in a proximal portion of the substantially tubular inner jacket, and proximal and distal seals mounted to the proximal and distal ends of the substantially tubular outer jacket for sealing the outer jacket.
In accordance with another aspect, the present invention is directed to a radioactive source ribbon assembly. The radioactive source ribbon assembly comprises a substantially tubular outer jacket having a proximal end and a distal end, the substantially tubular outer jacket being adapted for use with a delivery catheter, a substantially tubular radiation resistant axial load bearing member encapsulated in an inner jacket and mounted within the outer jacket, a radioactive source positioned in a distal portion of the encapsulated substantially tubular radiation resistant axial load bearing member, a core positioned in a proximal portion of the encapsulated substantially tubular radiation resistant axial load bearing member, and proximal and distal seals mounted to the proximal and distal ends of the substantially tubular outer jacket for sealing the outer jacket.
The radioactive source ribbon assembly of the present invention is utilized to deliver therapeutic doses of radiation to various regions of the human anatomy. The radioactive source ribbon assembly comprises an inner assembly and an outer jacket. The inner assembly includes a radioactive source, a core and a radiation resistant sleeve. The radioactive source and the core are encased in the radiation resistant sleeve to provide increased axial strength for the source ribbon assembly. The outer jacket comprises a lubricious material, for example, a polymeric material which encases the inner assembly. The radioactive source ribbon assembly is delivered to the appropriate region of the human anatomy via a sheath or catheter. Accordingly, the lubricious material forming the outer jacket provides a reduced friction interface for ease of insertion and removal of the assembly from the sheath or catheter.
The radiation resistant sleeve may be formed from any number of radiation resistant materials such as stainless steel. The radiation resistant sleeve comprises a braided tubular structure which encapsulates the radioactive source and the core. The braided tubular structure provides the assembly with increased tensile strength without sacrificing flexibility. In addition, the braided structure allows for an expanded number of materials to be used for the outer jacket by serving as the primary axial load member of the assembly and reducing concerns related to the strength degradation of the outer jacket. The radiation resistant sleeve also provides a secondary containment layer in the unlikely event of an outer jacket breach.
The radioactive source ribbon assembly of the present invention may be utilized any number of times over a given predetermined period of time. Once the predetermined period of time is achieved, the entire assembly is disposed of according to well-known radioactive disposal practices.